In commercial processes generally used for making chemically embossed sheets of resinous materials to be used, for example, as floor, wall, desk or table coverings, a liquid or semi-liquid, potentially foamable plastisol composition containing a blowing or foaming agent is applied substantially uniformly as a relatively thin uniform coating to the surface of a backing sheet material. The potentially foamable plastisol composition is then gelled to a relatively firm state by being heated at a controlled elevated temperature for a required period of time. The elevated temperature is controlled and is kept sufficiently low that gelling of the potentially foamable plastisol composition takes place without activating or decomposing the blowing or foaming agent and without creating any blowing or foaming of the potentially foamable plastisol composition.
Printing ink compositions, some of which contain blow-modifiers, which term includes blow-inhibitors, suppressants, accelerators, retarders, promoters, etc., are then applied to the surface of the gelled, potentially foamable plastisol composition in desired patterns and designs and the printed potentially foamable plastisol composition is then dried, again without creating any blowing or foaming. As used herein, the term "blow-modifier" is used to comprise any material included in a printing ink or other composition which is intended to alter the temperature at which blowing or foaming takes place, or the extent to which such blowing or foaming occurs.
Subsequently, when the gelled, potentially foamable plastisol composition with the printing ink compositions applied thereto in the desired designs or patterns is heated to a controlled, sufficiently higher temperature as to bring about blowing or foaming, those patterned areas printed with a blow-modifier printing ink composition are affected and their blowing and foaming modified accordingly, whereas those patterned areas not printed with any blow-modifying printing ink compositions blow or foam normally, whereby the differential blowing or foaming effect and the chemically embossed effects are created.
More specific details and the use of printing ink compositions containing blow-modifiers are to be found in U.S. Pat. Nos. 3,293,094 and 3,293,108 which issued on Dec. 20, 1966 to R. F. Nairn et al.